Is Twitch a publicly traded company?
If you are searching for the Twitch ticker symbol you are too late as Jeff Bezos bought the whole company for Amazon back in August 2014 for $970 million USD as part of Justin.tv. Twitch was first introduced in June 2011 as a spin-off of the original streaming platform Justin.tv. Twitch is a live video streaming service primarily used by video gamers playing in real time and it also broadcasts esports competitions. It has video on demand features as well. Twitch had 3 million broadcasters monthly and 15 million daily active users by February 2020. 
If you want to invest in Twitch you can only do so by buying Amazon stock. This will give you a share of ownership in the equity of Twitch as a part of the Amazon ecosystem. In the long term Twitch could turn out to be a great acquisition by Amazon much like YouTube was for Google. To invest in Twitch you must buy the full portfolio of Amazon holdings by investing in AMZN stock.